Android NativeCall crashes on Join

I have cloned and built the NativeCall example application for Android. When I try to run it on my Samsung Galaxy S7 Edge running Android 6.0.1, I can get the application to launch, but as soon as I try to join a room, the application gets a `SIGABRT`. The log in adb shows nothing, but if I run it in the debugger I can get a call stack for the exception, which looks like this:

thread #12: tid = 7719, 0xf7035538 libc.so`tgkill + 12, name = 'Thread-579', stop reason = signal SIGABRT

    frame #0: 0xf7035538 libc.so`tgkill + 12

    frame #1: 0xf703313c libc.so`pthread_kill + 36

    frame #2: 0xf700f786 libc.so`raise + 14

    frame #3: 0xf700c9f4 libc.so`__libc_android_abort + 38

    frame #4: 0xf700a5b0 libc.so`abort + 8

    frame #5: 0xf4250c48 libart.so`art::Runtime::Abort() + 216

    frame #6: 0xf4022d20 libart.so`art::LogMessage::~LogMessage() + 2216

    frame #7: 0xf417ecf2 libart.so`art::JavaVMExt::JniAbort(char const*, char const*) + 1530

    frame #8: 0xf417f092 libart.so`art::JavaVMExt::JniAbortV(char const*, char const*, std::__va_list) + 58

    frame #9: 0xf402b10e libart.so`art::ScopedCheck::AbortF(char const*, ...) + 34

    frame #10: 0xf402ffea libart.so`art::ScopedCheck::Check(art::ScopedObjectAccess&, bool, char const*, art::JniValueType*) (.constprop.95) + 5058

    frame #11: 0xf403e12a libart.so`art::CheckJNI::CallMethodV(char const*, _JNIEnv*, _jobject*, _jclass*, _jmethodID*, std::__va_list, art::Primitive::Type, art::InvokeType) + 642

    frame #12: 0xf403ec00 libart.so`art::CheckJNI::CallStaticIntMethod(_JNIEnv*, _jclass*, _jmethodID*, ...) + 40

    frame #13: 0xdf18347e libopenwebrtc_jni.so`VCD_getNumberOfCameras + 90 at android_video_capture_device.c:1470

    frame #14: 0xdf185006 libopenwebrtc_jni.so`VCD_open(logInterval=2000000) + 162 at android_video_capture_device.c:790

    frame #15: 0xdf17f82a libopenwebrtc_jni.so`gst_android_video_source_change_state(p_element=0xdec380e0, transition=GST_STATE_CHANGE_NULL_TO_READY) + 146 at gst_android_video_source.c:207

    frame #16: 0xdf4b4678 libopenwebrtc_jni.so`gst_element_change_state(element=0xdec380e0, transition=) + 20 at gstelement.c:2604

    frame #17: 0xdf4b4a06 libopenwebrtc_jni.so`gst_element_set_state_func(element=0xdec380e0, state=) + 338 at gstelement.c:2560

    frame #18: 0xdf4a0a6a libopenwebrtc_jni.so`gst_bin_change_state_func + 128 at gstbin.c:2328

    frame #19: 0xdf4a09ea libopenwebrtc_jni.so`gst_bin_change_state_func(element=0xdbd6cbc0, transition=GST_STATE_CHANGE_NULL_TO_READY) + 1858 at gstbin.c:2676

    frame #20: 0xdf4cb4e4 libopenwebrtc_jni.so`gst_pipeline_change_state(element=0xdbd6cbc0, transition=GST_STATE_CHANGE_NULL_TO_READY) + 268 at gstpipeline.c:474

    frame #21: 0xdf4b4678 libopenwebrtc_jni.so`gst_element_change_state(element=0xdbd6cbc0, transition=) + 20 at gstelement.c:2604

    frame #22: 0xdf4b4a06 libopenwebrtc_jni.so`gst_element_set_state_func(element=0xdbd6cbc0, state=) + 338 at gstelement.c:2560

    frame #23: 0xdf28d7be libopenwebrtc_jni.so`owr_local_media_source_request_source(media_source=0xf31071e0, caps=0xe99ac768) + 1258 at owr_local_media_source.c:661

    frame #24: 0xdf27e63a libopenwebrtc_jni.so`_owr_media_source_request_source(media_source=0xf31071e0, caps=0xe99ac768) + 74 at owr_media_source.c:562

    frame #25: 0xdf28e7a0 libopenwebrtc_jni.so`maybe_start_renderer(renderer=0xf2e42508) + 92 at owr_media_renderer.c:307

    frame #26: 0xdf28ec58 libopenwebrtc_jni.so`set_source(args=0xe9c036f0) + 220 at owr_media_renderer.c:367

    frame #27: 0xdf5d6e38 libopenwebrtc_jni.so`g_main_context_dispatch + 112 at gmain.c:3210

    frame #28: 0xdf5d6dc8 libopenwebrtc_jni.so`g_main_context_dispatch(context=0xf3148d20) + 96 at gmain.c:3874

    frame #29: 0xdf5d6fe0 libopenwebrtc_jni.so`g_main_context_iterate(context=0xf3148d20, block=, dispatch=1, self=0x00000012) + 252 at gmain.c:3945

    frame #30: 0xdf5d7288 libopenwebrtc_jni.so`g_main_loop_run(loop=0xee2d5560) + 208 at gmain.c:4139

    frame #31: 0xdf27ce42 libopenwebrtc_jni.so`owr_run + 58 at owr.c:350

    frame #32: 0xdf27ceb0 libopenwebrtc_jni.so`owr_run_thread_func(msg_queue=) + 80 at owr.c:332

    frame #33: 0xdf5ebe0a libopenwebrtc_jni.so`g_thread_proxy(data=0xf317d980) + 82 at gthread.c:764

    frame #34: 0xf7032a3c libc.so`__pthread_start(void*) + 32

  * frame #35: 0xf700d086 libc.so`__start_thread + 8

best I can tell, it's related to the `VCD_getNumberOfCameras` method. Is there something special I need to do here?

Start with the NativeCall Android example and inspect VCD_getNumberOfCameras and VCD_open in android_video_capture_device.c, especially the lines shown in the stack trace. Reproduce a room join on Android 6.0.1 under the debugger, identify the JNI failure, and verify that joining no longer ends in SIGABRT.

Written by the indexing model from the issue text.